Background:Few studies have examined the association between use of aspirin or other non-steroidal anti-inflammatory drugs (NSAIDs) and risk of glioma and the results have been equivocal. We therefore investigated the influence of NSAID use on glioma risk in a nationwide setting.Methods:We used national registries in Denmark to identify all patients aged 20-85 years with a first diagnosis of histologically verified glioma during 2000-2009. Each case was matched on birth year and sex to eight population controls using risk-set sampling. We used prescription data to assess NSAID use and classified exposure to low-dose aspirin or non-aspirin (NA) NSAIDs into ever use or long-term use, defined as continuous use for 5 years. Conditional logistic regression was used to compute odds ratios (ORs), with 95% confidence intervals (CIs), for glioma associated with NSAID use, adjusted for potential confounders.Results:A total of 2688 glioma cases and 18 848 population controls were included in the study. Ever use of low-dose aspirin (OR=0.90; 95% CI: 0.77-1.04) or NA-NSAIDs (OR=1.05; 95% CI: 0.96-1.14) was not associated with glioma risk. Compared with never use, long-term use of low-dose aspirin or of NA-NSAIDs was associated with ORs of 0.80 (95% CI: 0.53-1.21) and 1.11 (0.57-2.17), respectively. We observed no clear patterns of risk in stratified analysis according to estimated doses of low-dose aspirin (100 mg, 150 mg).Conclusion:We did not find any apparent association between aspirin or NA-NSAID use and risk of glioma, although our results may be consistent with a slight reduction in glioma risk with long-term use of low-dose aspirin.British Journal of Cancer advance online publication, 28 February 2013; doi:10.1038/bjc.2013.87 www.bjcancer.com.